Abstract: A dual exhaust system includes a first exhaust component defining a first exhaust path and a second exhaust component defining a second exhaust path that is different from the first exhaust path. A first valve is associated with the first exhaust path and a second valve is associated with the second exhaust path. The first valve and second valve operate independently of each other to vary exhaust flow and provide sufficient noise control for varying applications.

Abstract: An exhaust system of an internal combustion engine and provided with: at least one first high acoustic attenuation path having a first inlet opening; at least one second low acoustic attenuation path having a second inlet opening; and at least one control valve, which is arranged at the second inlet opening of the second path to control the flow of the exhaust gases along the second path.

Abstract: The invention relates to a retainer device for retaining a reducing agent metering valve. The retainer device at least partially surrounds an interior space which is provided for holding the reducing agent metering valve. According to the invention, the retainer device has a sound dampening device which dampens sound vibrations emerging from the interior space.

Abstract: An exhaust flow control valve includes: a valve plate hinged to a downstream exhaust pipe to be pivotable, inside the pipe, between a fully closed position where a short-cut hole is closed and a fully open position where the short-cut hole is opened, the valve plate having a tip end directed toward a downstream side of the downstream exhaust pipe when at the fully open position; a spring receiving member provided to the downstream exhaust pipe to traverse the short-cut hole; and a valve spring having one end portion fastened to a tip end portion, which is located on the downstream side of the downstream exhaust pipe with respect to the spring receiving member, of the valve plate, and having an opposite end side being slidably in pressure contact with the spring receiving member, thereby generating a repulsive force to bias the valve plate toward the fully closed position.

Abstract: A valve suitable for closing an orifice (36) of a structure (10) of a silencer (1) for a motor vehicle exhaust line, includes a closing component (44) which is connectable to the structure (10) and capable of adopting a position for closing the orifice (36). The closing component (44) is capable of rising by bending from its closure position. The closing component (44) includes a closure plate (54) capable of closing the orifice (36) and at least one connection plate (56) capable of connecting the closure plate (54) to the structure (10), the closure plate (54) and the or each connection plate (56) having differing thicknesses and/or being made of materials having differing mechanical characteristics.

Abstract: Various embodiments of reduced-size vehicles such as all-terrain vehicles (ATVs) and utility vehicles (UVs) are disclosed herein. In at least some embodiments, the vehicles include frames that are wider near the front and rear sections of the vehicles than within the mid-sections of the vehicles. This, in combination with the use of shock-absorbers that are substantially vertically oriented, allows for the opening-up of large interior cavities within the front and rear sections of the vehicles within which can be positioned large front and rear internal compartments that can provide storage/carrying capacity as well as added buoyancy for the vehicle, among other things. Also, in at least some embodiments, the vehicles can include special cooling and/or exhaust systems having components that are positioned substantially within the mid-sections of the vehicles, thus further increasing the amounts of space available for the cavities/compartments within the front and rear sections of the vehicles.

Abstract: A condensed water discharge apparatus is capable of smoothly excreting residual condensed water in a muffler. The device may include a through hole formed at the bottom of a muffler case, an inflow pipe communicated to the muffler case and in which exhaust gas flows, an exhaust pipe communicated to the atmosphere so that exhaust gas is exhausted from the muffler case thereto, a thermoelement, and a control valve mounted at the through hole so as to selectively open/close the through hole when driving or stopped by sliding about the through hole.

Abstract: A method and system for reducing pulsation in a gas compressor system. A pulsation control device, such as a filter bottle or side branch absorber, is installed at a port into some location on the compressor system. The pulsation control device has a choke tube with a variable cross-sectional area, such as by having multiple conduits that may be opened or closed or a diameter that may be varied. In operation, the cross sectional area of the choke tube is varied depending on the compressor speed.

Abstract: An exhaust throttle valve protected from disturbance due to stones scattered during operation of a vehicle. Front side exhaust pipes and rear side exhaust pipes are connected to a catalyst chamber disposed below a crankcase. The catalyst chamber and an exhaust chamber disposed to the rear thereof are connected to each other via a rear exhaust pipe. The diameter of the rear exhaust pipe is smaller than the lateral width of each of the catalyst chamber and the exhaust chamber, so that a recessed space is externally formed so as to recede inside of the vehicle. An exhaust throttle valve is received in the space. The exhaust throttle valve is partially exposed to the outside of the rear exhaust pipe and a throttle valve is received in the rear exhaust pipe to throttle-control the passage-sectional area of the rear exhaust pipe according to the rotation of the engine.

Abstract: An aircraft turbine engine with a takeoff fan speed and a landing fan speed, the aircraft engine includes a fan duct with a HQ (Herschel-Quincke) acoustic control noise reduction tube. The acoustic control noise reduction tube contains a movable frequency tuner obstruction. The movable frequency tuner obstruction is movable within the acoustic control noise reduction tube, with the movable frequency tuner obstruction movable along a fixed tube path length between a first takeoff frequency obstruction tube path location, and a second landing frequency obstruction tube path location, with the frequency tuner obstruction positioned at the first takeoff frequency location with the takeoff speed, and the frequency tuner obstruction positioned at the second landing frequency location with the landing speed to reduce noise.

Abstract: An intake sound adjusting device includes an intake passage, a tubular branch passage branched from the intake passage, and an oscillating member disposed within the branch passage, in which the oscillating member has an oscillating portion disposed so as to close an interior of the branch passage and a controlling portion extending from the oscillating portion in a direction along an extending direction of the branch passage.

Abstract: A muffler apparatus for a vehicle, may include a muffler housing; baffle plates that are disposed in the muffler housing and divides an internal space of the muffler housing; an intake pipe that is supported by at least one of the baffle plates and takes in exhaust gas; and an exhaust pipe that is supported by at least one of the baffle plates and takes in the exhaust gas discharged from the intake pipe and discharges the exhaust gas outside the muffler housing, and of which a pipe line of the exhaust pipe circulates through the internal space of the muffler housing.

Abstract: A variable resonation chamber valve includes an outer valve seat and a rotatable plunger. The outer valve seat defines an inlet opening into an associated resonation chamber. The rotatable plunger is movable into the inlet opening of the valve seat for varying a tuner area of the inlet opening.

Abstract: A muffler for an internal combustion engine featuring two flowpaths for exhaust through the muffler. A first serpentine pathway is substantially longer than a second pathway through the muffler, thereby providing increased sound attenuation. Temperature activated internal valves operate to change the exhaust flowpath from the first flowpath to the second flowpath through the muffler as exhaust gasses warm the muffler and the temperature actuated valves.

Abstract: A high-performance muffler assembly for exhaust system of an internal combustion engine. The muffler assembly comprises an elongated casing having an inlet port and an exit port, a first pipe disposed within the casing and having an inlet end in fluid communication with the inlet port and an outlet end selectively fluidly connected to the exit port of the casing, and a first valve mounted within the casing. The first valve is selectively movable between a closed position and an open position for regulating an exhaust gas flow through the first pipe. The muffler assembly is operable in a number of different modes of operation including a high-performance mode, an exhaust braking mode, a reverse-flow mode, etc., determined by the positions of the first valve of the muffler assembly.

Abstract: Disclosed are apparatus and methodology for reducing noise and wear in a flapper configured exhaust tip for a marine exhaust system. A flapper, normally located within an exhaust tip of a marine exhaust system, is relocated upstream of the point in the exhaust system where cooling water normally contacts the exhaust pipe. An exhaust tip is coupled to the upstream portion of the exhaust system by way of an elastomeric coupling device. The flapper is positioned such that a tip thereof contacts the elastomeric coupling rather than the metallic exhaust pipe. Such contact with an elastomeric coupling device reduces noise previously produced by flapper contact with the hot exhaust pipe occasioned by destruction and/or heat degeneration of elastomeric material generally associated with the flapper device.

Abstract: An exhaust valve and a catalyst can be easily disposed of in a simple manner. The interior of a triangular muffler is partitioned into three expansion chambers. A manifold pipe is connected to the second, middle expansion chamber sideways from a lower portion thereof and is accommodated therein so as to face upward. A catalyst is accommodated in the interior of the manifold pipe. Exhaust gas flowing out from an open end of the manifold pipe expands into the second chamber. A short-circuiting aperture is formed in a second separator and is opened and closed with an exhaust valve installed within the third chamber. The exhaust valve is normally closed by a spring. When the exhaust pressure reaches a predetermined magnitude, the exhaust valve opens automatically, allowing the exhaust gas to flow out into the third chamber through the short-circuiting aperture, thereby controlling the exhaust pressure.

Abstract: An auto-sensing, automatic adjusting exhaust baffle; for reducing noise emissions produced by internal combustion engines, while improving overall engine performance, i.e., torque and horsepower. The design uses a spherical shape to evacuate spent exhaust gas, thus scavenging the surrounding exhaust gases to adjust the backpressure, while reducing the noise exiting the exhaust pipe at lower rpm's. The device uses a sphere with an internal bearing; sliding linearly on a shaft and said sphere and bearing being acted upon by exhaust gasses and a compression spring mounted axially over the diameter of the shaft. The purpose of this device is to reduce noise while improving tuning of the air/fuel intake system, by adjusting backpressure of the exhaust system. The lesser amount of exhaust pressure, the less the sphere moves, as in idle to just off of idle, this results in a quiet operational mode of the invention.

Abstract: Snap action valve assemblies for use in conduits of automotive exhaust systems have their operation controlled by use of inertia damper elements coupled to an axle of a rotatable valve plate of the valve assembly.

Abstract: The invention relates to a silencer for an airborne sound conducting pipe system, including a housing enclosing an interior space, an inlet pipe having an outlet within the interior space, a bypass pipe branching off from inlet pipe within the housing and having an outlet, a control element actuated by the gas flow and arranged downstream of bypass pipe on or in the inlet pipe, and at least one outlet pipe having an inlet within the interior space. Furthermore, the interior space is acoustically unseparated in such a manner that the volume of the interior space loaded with the airborne sound is equal with opened and with closed control element.

Abstract: A vehicle (1) is provided with an exhaust pipe (2) extending from an engine mounted in the front part of the vehicle to a branch part (24) in the rear part of the vehicle, and right and left branch pipes (25, 26) extending from the branch part to mufflers (5, 6) on both right and left sides. The branch part (24) is arranged so as to be offset to the side of either one muffler (5) of the right and left mufflers with respect to the center in the vehicle width direction; the exhaust pipe has an upstream part (2, 21) laid linearly to a bend part (22) positioned in the center in the vehicle width direction near the rear end of a fuel tank, and an oblique part (23) laid slantwise from the bend part toward the branch part; and the length of the branch pipe (25) having a longer distance to the muffler is approximately equal to the length of the oblique part (23).

Abstract: An automotive muffler having a device for switching between loud and quieter modes includes a chamber having an inlet exhaust pipe and an outlet exhaust pipe for the passage of exhaust gases through the chamber. The first section of the chamber has a plurality of baffles with openings through the baffles for the passage of the exhaust gases. A second section of the chamber, separated from the first section of the chamber, permits a substantially unobstructed passage of exhaust gases through the second section of the chamber to the outlet exhaust pipe.

Abstract: A muffler for efficiently reducing noise. Front side exhaust pipes and rear side exhaust pipes extend from front cylinders and rear cylinders, respectively, of a V-type water-cooled 4-cylinder engine and are operatively connected to a catalyst chamber disposed below a crankcase. The catalyst chamber is connected to an exhaust chamber located to the rear thereof in which exhaust gas is expanded. An outlet pipe laterally projects from a lateral surface of a rear end portion of the exhaust chamber and is connected to a front pipe projecting from the lateral surface of the front portion of a muffler. The front pipe is transversely inserted into the muffler to increase a cross-section ratio, thereby efficiently reducing noise.

Abstract: A muffler is disclosed. In the muffler a throttling device that is controlled by the energy of the airflow to be muffled is provided in a pipeline of the airflow that needs to be muffled. The muffler is adjusted by itself according to random variety of the pulsing airflow, and can eliminate or reduce effectively the pulsation of the airflow and the related noise in the range of the low frequency and the middle frequency. The muffling effect of the muffler has no correlation with the volume of the muffler, and therefore the volume of the muffler can be reduced.

Abstract: A passive, exhaust pressure actuated valve assembly for placement inside a tubular exhaust conduit is pivotally mounted to an off-center axle for rotation between fully closed and fully opened positions. A bias element forces the valve flap toward the fully closed position. The valve flap is shaped in a manner enabling use of the interior surface of the exhaust conduit to define stops at the full closed and full opened positions. The valve flap shape, in conjunction with the bias element arrangement, enables the flap to lie substantially parallel to a longitudinal axis of the conduit in the fully opened position, which provides for minimum back pressure in the conduit. The valve assembly finds particularly advantageous use inside a bypass through pipe of a muffler assembly.

Abstract: A muffler has a casing with a plurality of sound-muffling chambers, exhaust pipes that pass through at least two sound-muffling chambers and to pass through exhaust from an engine, a plurality of apertures provided in each exhaust pipe, and a plurality of valves provided in each of the apertures. In this muffler, the plurality of apertures are provided at the locations at which an exhaust flow from one aperture and an exhaust flow from another aperture do not interfere with each other. When there are two apertures, the apertures are provided at positions in the exhaust pipes at which the apertures do not face each other. For this reason, by avoiding interference between exhaust flows from the two apertures, it is possible to suppress an abnormal sound caused by the interference.

Abstract: A high-performance muffler assembly for exhaust system of an internal combustion engine. The muffler assembly comprises an elongated casing having an inlet port and an exit port, a first pipe disposed within the casing and having an inlet end in fluid communication with the inlet port and an outlet end selectively fluidly connected to the exit port of the casing, and a first valve mounted within the casing. The first valve is selectively movable between a closed position and an open position for regulating an exhaust gas flow through the first pipe. The muffler assembly is operable in a number of different modes of operation including a high-performance mode, an exhaust braking mode, a reverse-flow mode, etc., determined by the positions of the first valve of the muffler assembly.

Abstract: An exhaust system of an internal combustion engine and provided with: at least one first high acoustic attenuation path having a first inlet opening; at least one second low acoustic attenuation path having a second inlet opening; and at least one control valve, which is arranged at the second inlet opening of the second path to control the flow of the exhaust gases along the second path.

Abstract: A flow passage control valve for a muffler may include an opening formed through a guide pipe, which forms an exhaust gas channel in the muffler, to form another exhaust gas channel, and a valve body adjusts an open amount of the opening by using a difference between an exhaust gas pressure exerted through the opening and a weight of the valve body.

Abstract: An exhaust system (1) is provided for an internal combustion engine (4), especially in a motor vehicle, with two separate exhaust gas lines (2, 3) with a first sound transmission feature (7), which couples the two exhaust gas lines (2, 3) with one another, and with a control (9) for activating and deactivating the first sound transmission connection (7) as a function of at least one operating parameter of the internal combustion engine (4).

Abstract: A low emissions 2-stroke natural gas fueled engine includes at least one cylinder with an exhaust port in communication with a silencer/catalytic converter unit. The unit has first and second volumes in communication with each other. The first volume dampens spurious exhaust pressure excursions and removes particulates in the exhaust. The second volume houses an oxidation catalyst for treating exhaust to reduce exhaust emissions. The engine oil has at most 10 ppm zinc content to reduce metal poisons contained in the exhaust prior to contact with the oxidation catalyst. The engine oil preferably has a very low ash content to minimize sulfur combustion components in the exhaust to reduce masking of the oxidation catalyst. The first volume preferably has a pressure relief valve set to relieve at a pressure greater than the maximum normal operating pressure of the engine to avoid excessive pressure excursions of the engine exhaust from damaging the oxidation catalyst.

Abstract: A dual-mode exhaust system includes a housing with an input port attached to the existing muffler exhaust system and positioned downstream thereof. The system further includes a mechanism for selectively distributing vehicle exhaust from the input port to the first and second output ports, upper and lower chambers vertically stacked within the housing, and first and second vertically spaced pendulum arms disposed within the upper and lower chambers respectively and anchored at respective distal ends thereof respectively. First and second vehicle exhaust pipes are coupled to the first and second output ports.

Abstract: The invention provides a muffler assembly (10) for exhaust gas flow communication with an engine exhaust. The assembly (10) includes a muffler (12) having inlet and outlet ports (14, 16). The assembly (10) also includes first and second flow of passages in common fluid communication with the outlet port (16) and in variable fluid communication with the inlet port (14). The first and second flow passages meet at first and second connecting points. The first connecting point is located in the proximity of the inlet port (14). The first flow passage has a higher resistance to fluid flow than the second flow passage. The assembly (10) also includes a valve means (24) generally located past the first connecting point inside the second flow passage for selectively proportionating exhaust gases passing through the passages. The first flow passage includes three or more conduits (26, 28, 30) being in fluid communication with each other.

Abstract: A high-performance muffler assembly for exhaust system of an internal combustion engine. The muffler assembly comprises an elongated casing having an inlet port and an exit port, a first pipe disposed within the casing and having an inlet end in fluid communication with the inlet port and an outlet end selectively fluidly connected to the exit port of the casing, and a first valve mounted within the casing. The first valve is selectively movable between a closed position and an open position for regulating an exhaust gas flow through the first pipe. The muffler assembly is operable in a number of different modes of operation including a high-performance mode, an exhaust braking mode, a reverse-flow mode, etc., determined by the positions of the first valve of the muffler assembly.

Abstract: An exhaust component includes at least one muffler that has an inlet and an outlet. One pipe body is connected to each of the inlet and the outlet. The pipe bodies each have first and second ends that define a respective overall pipe length. Each pipe body defines a sole exhaust flow path between their first and second ends. A passive valve assembly is mounted outside of the muffler and within one of the pipe bodies. The passive valve assembly is positioned at a location within a first 25% of the overall pipe length of one of the pipe bodies relative to the inlet or outlet of the muffler.

Abstract: A dual mode exhaust muffler for the engine of a vehicle that may be shifted between a quiet mode and a loud mode. A single muffler, a dual transverse muffler with two independent exhaust flow streams, and a dual transverse muffler with a combined exhaust flow stream embodiments are disclosed. An inlet tube may be a solid wall tube to minimize sound attenuation in the loud mode. The dual transverse muffler embodiments utilize an exhaust flow path that passes out through a reticulated wall of one tube and passes into a reticulated wall of a second tube. A vacuum switch having a two position on/off slide actuator may be used with any of the muffler assemblies.

Abstract: A muffler has a casing with a plurality of sound-muffling chambers, exhaust pipes that pass through at least two sound-muffling chambers and to pass through exhaust from an engine, a plurality of apertures provided in each exhaust pipe, and a plurality of valves provided in each of the apertures. In this muffler, the plurality of apertures are provided at the locations at which an exhaust flow from one aperture and an exhaust flow from another aperture do not interfere with each other. When there are two apertures, the apertures are provided at positions in the exhaust pipes at which the apertures do not face each other. For this reason, by avoiding interference between exhaust flows from the two apertures, it is possible to suppress an abnormal sound caused by the interference.

Abstract: A muffler assembly includes first and second muffler components that are each formed as a single piece. The first muffler component includes a first outlet pipe portion, a first bypass pipe mount portion, and a first resonator shell portion. The second muffler component includes a second output pipe portion, a second bypass pipe mount portion, and a second resonator shell portion. The first and second muffler components are positioned in an overlapping relationship such that respective portions are aligned with each other to form an outlet pipe, a bypass pipe mount, and a resonator shell. A noise attenuation valve assembly is also installed within the first and second muffler components. The bypass pipe mount is positioned at a non-perpendicular orientation relative to the outlet pipe such that a bypass pipe having a straight end mount can be received within the bypass pipe mount to bypass the noise attenuation valve assembly.

Abstract: A rear muffler assembly for an internal combustion engine has a first and a second muffler through which exhaust gases flow and which are separated from one another. The first and second mufflers have in each case an exhaust gas delivery and discharge through an exhaust gas routing pipe issuing into an exhaust pipe which follows downstream and in which an exhaust gas shutoff flap which can be closed temporarily is disposed. The rear muffler assembly contains two exhaust gas routing pipes, the first exhaust gas routing pipe having within the rear muffler an issue orifice for exhaust gases positively emerging from the second exhaust gas routing pipe, with the exhaust gas shutoff flap closed, into which first exhaust gas routing pipe the exhaust gases from the internal combustion engine flow directly.

Abstract: An exhaust component includes at least one muffler that has an inlet and an outlet. One pipe body is connected to each of the inlet and the outlet. The pipe bodies each have first and second ends that define a respective overall pipe length. Each pipe body defines a sole exhaust flow path between their first and second ends. A passive valve assembly is mounted outside of the muffler and within one of the pipe bodies. The passive valve assembly is positioned at a location within a first 25% of the overall pipe length of one of the pipe bodies relative to the inlet or outlet of the muffler.

Abstract: The invention uses tubes for the reduction of radiated duct noise. The tubes may be used to attenuate narrow band noise by diverting a portion of the acoustic energy through the tubes back into the duct. Upon reintroducing the diverted flow out of phase with the primary flow, acoustic cancellation is achieved. The frequency at which this occurs is dependent on the difference in the path lengths through the tubes and the separation distance—the distance separating the inlet and outlet of the tube. This invention can be used over varying frequency ranges by using an arrangement of flexible, constant length tubes. The effective frequency range is tailored by varying the separation distance and also allows the varying the angular arrangement of the tubes for more effective attenuation of spinning modes having varying propagation angle.

Abstract: A single valve member is provided for selecting communication of one of two flow passages constituting an exhaust flow passage, and continuously providing a flow passage area of the selected one of the two flow passages. According to this valve member, a changeover of flow passage between a main flow passage with an exhaust processing device disposed therein and a bypass flow passage is performed, and each flow passage area is regulated, to meet an output requirement, exhaust processing requirement and muffling requirement, appropriately. For example, a single valve member 5 is disposed on the upstream side or downstream side of a start catalytic converter 3, whereby communication of one of a main flow passage 1 and a bypass flow passage 2 is selected, and a flow passage area of the selected passage is continuously provided.

Abstract: A switchable exhaust system apparatus. The switchable exhaust system apparatus is switchable between a quiet or normal mode and a loud mode when desired.

Abstract: The invention relates to a muffler for an exhaust system of an internal combustion engine, consisting a housing having at least one exhaust inlet and at least one exhaust outlet and having at least two pipes at the inlet end or at the outlet end, at least one of which is switchable by a control device at least between an open state and a closed state and is acoustically coupled to a silencer system, such that the silencer system is active when the switchable pipe is opened as well as when it is closed and has a different damping characteristic when the switchable pipe is opened than when the switchable pipe is closed.

Abstract: A muffler outlet part for a muffler to be used in exhaust systems of motorcycles has at least one main body disposed transversely to an outflow direction of exhaust gas and having a center axis, the main body having a centrical first outlet opening disposed concentrically relative to the center axis for the outflow of exhaust gas from an outlet chamber of the muffler, and at least one second outlet opening disposed eccentrically relative to the center axis for the outflow of exhaust gas from an expansion chamber of the muffler, said expansion chamber enclosing the outlet chamber. It further has at least one closing member that is swivel-mounted about the center axis for an at least partial closing of the at least one second outlet opening, and at least one adjustment element for swiveling of the closing member via an adjustment means, which cooperates in a torque-transmitting manner with the at least one adjustment element.

Abstract: A dynamic exhaust system including a down-pipe (1) to receive exhaust gases from the engine and delivering the gases to an exhaust pipe (3). The system further includes a valve member (11) with one end extending through the exhaust pipe inlet and into the down-pipe (1). The valve (11) is movable to reduce or increase the area of the inlet port (2) of the exhaust pipe (3).

Abstract: A low emissions 2-stroke natural gas fueled engine includes at least one cylinder with an exhaust port in communication with a silencer/catalytic converter unit. The unit has first and second volumes in communication with each other. The first volume dampens spurious exhaust pressure excursions and removes particulates in the exhaust. The second volume houses an oxidation catalyst for treating exhaust to reduce exhaust emissions. The engine oil has at most 10 ppm zinc content to reduce metal poisons contained in the exhaust prior to contact with the oxidation catalyst. The engine oil preferably has a very low ash content to minimize sulfur combustion components in the exhaust to reduce masking of the oxidation catalyst. The first volume preferably has a pressure relief valve set to relieve at a pressure greater than the maximum normal operating pressure of the engine to avoid excessive pressure excursions of the engine exhaust from damaging the oxidation catalyst.

Abstract: The invention relates to a silencer for an airborne sound conducting pipe system, including a housing enclosing an interior space, an inlet pipe having an outlet within the interior space, a bypass pipe branching off from inlet pipe within the housing and having an outlet, a control element actuated by the gas flow and arranged downstream of bypass pipe on or in the inlet pipe, and at least one outlet pipe having an inlet within the interior space. Furthermore, the interior space is acoustically unseparated in such a manner that the volume of the interior space loaded with the airborne sound is equal with opened and with closed control element.

Abstract: A muffler for an exhaust gas system of an internal-combustion engine has an exhaust gas inlet and a first flow pipe arranged inside the muffler and completely penetrating the muffler. A shut-off device is arranged in the first flow pipe, for the shutting-off and opening-up an exhaust gas tail pipe which is situated downstream of the muffler and is connected with the first flow pipe. A second flow pipe partially penetrates the muffler, and has an overflow path between the first and second flow pipes situated inside the muffler. The first and the second flow pipes are connected with the exhaust gas inlet by way of a branching element and the shut-off device is arranged upstream of the muffler in the first flow pipe.

Abstract: An exhaust sound controlling method including reducing a flow rate of exhaust gas that passes through an exhaust path, to a first flow rate in accordance with increase in engine speed in a first engine speed region, and increasing the flow rate of exhaust gas to a second flow rate in accordance with increase in engine speed in a second engine speed region higher in engine speed than the first engine speed region. An exhaust sound controlling apparatus including a baffle plate and a valve that is operated to open a communication passage that communicates upstream and downstream sides of the baffle plate in an engine starting region, close the communication passage in an idling region and a low engine speed region, and open the communication passage and increase an opening of the valve as the engine speed rises in a high engine speed region.